1. Field of the Invention
The present invention relates to a synthetic resin swivel hook for use in various kinds of bags, knapsack and the like.
2. Description of the Related Art
Recently, instead of a metallic swivel hook, synthetic resin swivel hook has been more often used because the synthetic resin swivel hook is composed of a smaller number of parts than the metallic swivel hook and the synthetic resin swivel hook ensures a better productivity and it is light and cheap. On the contrary, the metallic swivel hook requires a larger number of parts, so that its assembly process is composed of more steps thereby leading to a higher price. Further, because the metallic swivel hook is difficult to paint with durable colors, it lacks of fashion performance so that it is not suitable for traveling bag, shoulder bag or the like. Thus, use of the metallic swivel hook is limited to particular sectors, for example, expensive goods.
An example of the synthetic resin swivel hook has been disclosed in, for example, Japanese Patent Laid-Open Publication No. 9-32839. This synthetic resin swivel hook comprises a hook body protruded from a base portion and a stopper piece which is protruded from the same base portion toward a tip end of the hook body and elastically deformed around a base end thereof. The hook body or stopper piece has a projection projecting from its inner face toward the stopper piece or the hook body provided near the base end and a height of a front end of the projection is set so that it comes into contact with the inner face of the stopper piece or inner face of the hook body within an elastic limit of the base end when the stopper piece is deformed.
In the swivel hook disclosed in this publication, because the hook body and/or the stopper piece has the projection having a desired height directed toward a counterpart on the inner face of the base end portion thereof, even if a strong outside force is applied to the base end portion of the stopper piece, deformation exceeding an elastic limit of the stopper piece is prevented by the aforementioned projection, so that a breaking of the base end portion of the stopper piece, which is the part easiest to be broken is prevented securely. Further, because an existence of the projection prevents a ring, which is attached to an end of a belt and engages the hook body, from moving to between the base ends of the hook body and stopper piece, even if an outside force is applied outward of the hook body by the ring, the ring is moved from the base end of the stopper piece to a front end thereof by the projection, thereby preventing the base end of the stopper piece from being damaged.
However, in the swivel hook disclosed in the above publication, because of the existence of the projection projecting from the inner face of the hook body or the stopper piece, after the same projection comes into contact with the opposing inner face of the stopper piece or hook body, a base end of rotation, when the stopper piece is elastically deformed in the direction to an inner face of the hook body, is moved from a projection end on the base portion to an edge of the projection on the side toward a front end of the hook body, an amount of rotation is reduced extremely. Thus, if it is intended to form an opening space sufficient for engaging the ring attached to the belt to the hook body, the depth and height of the hook body need to be larger than conventionally. As a result, there is produced an adverse effect that the swivel hook itself is enlarged. If an outside force exceeding the aforementioned elastic limit is applied to the stopper piece near the front end of the hook body with respect to the projection, the stopper piece may be broken at the edge of the projection on the side of the front end of the hook body.
As disclosed by U.S. Pat. No. 5,146,657 for example, the conventional synthetic resin swivel hook is formed with the stopper piece slightly off a front end outer surface of the hook body and after the formation, the stopper piece is elastically deformed to fit onto an inside fitting face at a front end of the hook body. Thus, a working amount for it cannot be neglected so that it affects production cost to some extent.